From 01ec20933dcfd569961ae0a82ada772ec6456096 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kevin=20L=C3=A4ufer?= <laeufer@cornell.edu>
Date: Tue, 19 Nov 2024 15:55:28 -0500
Subject: [PATCH] add is_one method

---
 Cargo.toml    |  2 +-
 src/bv/ops.rs | 19 +++++++++++++++++--
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 5ef6e34..cd13ec6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "baa"
-version = "0.14.2"
+version = "0.14.3"
 edition = "2021"
 authors = ["Kevin Laeufer <laeufer@cornell.edu>"]
 description = "BitVector and Array Arithmetic"
diff --git a/src/bv/ops.rs b/src/bv/ops.rs
index 7b32fb9..01cd4b9 100644
--- a/src/bv/ops.rs
+++ b/src/bv/ops.rs
@@ -197,13 +197,18 @@ pub trait BitVecOps {
         self.words().iter().all(|w| *w == 0)
     }
 
+    fn is_one(&self) -> bool {
+        let msbs_are_zero = self.words().iter().skip(1).all(|w| *w == 0);
+        msbs_are_zero && self.words()[0] == 1
+    }
+
     fn is_all_ones(&self) -> bool {
-        let lsbs_zero = self
+        let lsbs_are_max = self
             .words()
             .iter()
             .take(self.words().len() - 1)
             .all(|w| *w == Word::MAX);
-        lsbs_zero && (*self.words().last().unwrap() == mask(self.width() % Word::BITS))
+        lsbs_are_max && (*self.words().last().unwrap() == mask(self.width() % Word::BITS))
     }
 
     fn is_negative(&self) -> bool {
@@ -606,4 +611,14 @@ mod tests {
         a.set_bit(1000);
         assert!(a.is_all_ones());
     }
+
+    #[test]
+    fn test_is_one() {
+        let mut a = BitVecValue::zero(23);
+        assert!(!a.is_one());
+        a.set_bit(0);
+        assert!(a.is_one());
+        a.set_bit(20);
+        assert!(!a.is_one());
+    }
 }